Brocade Communications Systems Layer 3 Routing Configuration ICX 6650 - Manual (Page 222)

204 Brocade ICX 6650 Layer 3 Routing Configuration Guide
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Configuring OSPF
Configuring external route summarization
When the Layer 3 Switch is an OSPF Autonomous System Boundary Router (ASBR), you can
configure it to advertise one external route as an aggregate for all redistributed routes that are
covered by a specified address range.
When you configure an address range, the range takes effect immediately. All the imported routes
are summarized according to the configured address range. Imported routes that have already
been advertised and that fall within the range are flushed out of the AS and a single route
corresponding to the range is advertised.
If a route that falls within a configured address range is imported by the Layer 3 Switch, no action is
taken if the Layer 3 Switch has already advertised the aggregate route; otherwise the Layer 3
Switch advertises the aggregate route. If an imported route that falls with in a configured address
range is removed by the Layer 3 Switch, no action is taken if there are other imported routes that
fall with in the same address range; otherwise the aggregate route is flushed.
You can configure up to 32 address ranges. The Layer 3 Switch sets the forwarding address of the
aggregate route to zero and sets the tag to zero.
If you delete an address range, the advertised aggregate route is flushed and all imported routes
that fall within the range are advertised individually.
If an external LSDB overflow condition occurs, all aggregate routes are flushed out of the AS, along
with other external routes. When the Layer 3 Switch exits the external LSDB overflow condition, all
the imported routes are summarized according to the configured address ranges.
NOTE
If you use redistribution filters in addition to address ranges, the Layer 3 Switch applies the
redistribution filters to routes first, then applies them to the address ranges.
NOTE
If you disable redistribution, all the aggregate routes are flushed, along with other imported routes.
To configure a summary address for OSPF routes, enter commands such as the following.
Brocade(config-ospf-router)#summary-address 10.1.0.0 255.255.0.0
The command in this example configures summary address 10.1.0.0, which includes addresses
10.1.1.0, 10.1.2.0, 10.1.3.0, and so on. For all of these networks, only the address 10.1.0.0 (the
parent route) is advertised in external LSAs. However, if the parent route has not been configured
with a summary address, or if the summary address for the parent route is configured after the
child route, the Layer 3 switch will advertise all routes. For example:
router ospf
area 0
summary-address 10.1.1.0 255.255.0.0 -> Advertised
summary-address 10.1.2.0 255.255.0.0 -> Advertised
summary-address 10.0.0.0 255.0.0.0 -> Advertised
Syntax: summary-address ip-addr ip-mask
The ip-addr parameter specifies the network address.
The ip-mask parameter specifies the network mask.